In late December 1951, Ruppelt met with members of the Battelle Memorial Institute, a think tank based in Columbus, Ohio. Ruppelt wanted their experts to assist them in making the Air Force UFO study more scientific. It was the Battelle Institute that devised the standardized reporting form. Starting in late March 1952, the Institute started analyzing existing sighting reports and encoding about 30 report characteristics onto IBM punched cards for computer analysis.
Project Blue Book Special Report No. 14 was their massive statistical analysis of Blue Book cases to date, some 3200 by the time the report was completed in 1954, after Ruppelt had left Blue Book. Even today, it represents the largest such study ever undertaken. Battelle employed four scientific analysts, who sought to divide cases into "knowns", "unknowns", and a third category of "insufficient information." They also broke down knowns and unknowns into four categories of quality, from excellent to poor. E.g., cases deemed excellent might typically involve experienced witnesses such as airline pilots or trained military personnel, multiple witnesses, corroborating evidence such as radar contact or photographs, etc. In order for a case to be deemed a "known", only two analysts had to independently agree on a solution. However, for a case to be called an "unknown", all four analysts had to agree. Thus the criterion for an "unknown" was quite stringent.
In addition, sightings were broken down into six different characteristics â color, number, duration of observation, brightness, shape, and speed â and then these characteristics were compared between knowns and unknowns to see if there was a statistically significant difference.
The main results of the statistical analysis were:
* About 69% of the cases were judged known or identified (38% were considered conclusively identified while 31% were still "doubtfully" explained); about 9% fell into insufficient information. About 22% were deemed "unknown", down from the earlier 28% value of the Air Force studies.
* In the known category, 86% of the knowns were aircraft, balloons, or had astronomical explanations. Only 1.5% of all cases were judged to be psychological or "crackpot" cases. A "miscellaneous" category comprised 8% of all cases and included possible hoaxes.
* The higher the quality of the case, the more likely it was to be classified unknown. 35% of the excellent cases were deemed unknowns, as opposed to only 18% of the poorest cases. This was the exact opposite of the result predicted by skeptics, who usually argued unknowns were poorer quality cases involving unreliable witnesses that could be solved if only better information were available.
* In all six studied sighting characteristics, the unknowns were different from the knowns at a highly statistically significant level: in five of the six measures the odds of knowns differing from unknowns by chance was only 1% or less. When all six characteristics were considered together, the probability of a match between knowns and unknowns was less than 1 in a billion.